Species | Psiloceras pseudocostosum Kment |
Author | KMENT |
Group | Psiloceraten |
Horizon | tibeticum-horizon |
Zone | tilmanni-zone |
Stage | Lower Hettangian |
Description
The body is evolute and the winding cross-section oval. The umbilical edge is rounded, the umbilical slope steep and the flank slightly curved. The venter is rounded.
A nodule stage could not be detected; the described specimens are not optimally preserved.
The ribs start leaning back at the navel edge, reach their greatest height on the inner part of the flank and then very quickly become weaker. A slight forward bend is visible before they die out, so that the ribs occupy only 2/3 of the flank. The ribs thus appear slightly bent in an S-shape. Irregularly large spaces between the ribs are often observed.
* Description according to Kment (2021)
Compare
The S-shaped ribbing, which occupies only part of the flank, is characteristic.
Psiloceras tibeticum has much fewer and much more bulging ribs. Psiloceras angulocostatum can also be distinguished in this way and is found much lower down.
Psiloceras strongolum is most similar, but has straighter ribs covering the whole flank.
The same applies to Psiloceras calliphyllum.
Dimension
Dimensions with D= 41mm
Nw % v. D: 50%
Wh % v. D: 27%
Wb % v. D: 22%
Literature
- 2021 Psiloceras pseudocostosum n. sp. – KMENT, S. 245, Abb. 5.7-5.9